Children in health and disease : a study of child-life.

  • Forsyth, David.
Date:
1909
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Licence: In copyright

Credit: Children in health and disease : a study of child-life. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    the heart and the cross-sectional area of the arteries. According to Landois, the child begins life with blood-vessels which are larger relative to the heart than at puberty or later. At birth the numerical ratio is given as 25:20, while at puberty it is 50: 140, and in adults 290:61. This striking increase indicates that the work of the heart is relatively less in early life, and it implies that the blood-pressure also is lower at that age.' Like the pulse-rate, the respiration-rate is fastest at birth. Beginning at 40 a minute, it has settled down to 30 by the end of the first year, to 25 by the fifth year, and to 20 by the sixteenth year. This gradual slowing is another effect of the ratio between volume and surface and its influence on heat- loss. All warm-blooded animals share in this effect, so that we find that while the rat breathes 210 times a minute, the lion breathes ten times, and the rhinoceros six times. Some difficulty arises in making an exact estimate of the respiration-rate in infancy, owing to the irregularity of rhythm that is characteristic of this age. Not only are the intervals between the breaths often unequal, but the special type of breathing known as Cheyne-Stokes breathing, which is patho- logical in adults, is physiological in infancy. This Cheyne- Stokes breathing consists of periods of increasing frequency and amplitude of respiration alternating with periods of slow, shallow breathing that culminate in complete inhibition, and this may often be observed in infants even during their quiet sleep. As might be expected, the function of the respiratory centre is less readily destroyed in the new-born than in older children, in whom it has become delicately susceptible to changes in the gaseous composition of the blood. This difference has been well illustrated experimentally in the case of animals. Full-grown guinea-pigs, for example, if immersed in water, are asphyxiated in from three to three and a half minutes, but new-born guinea- pigs can survive the want of oxygen for four times as long. Kidneys.—Passing next to the excretory functions of the kidney, we find that they are in full action shortly after birth. While less than 50 c.c. of urine may be voided during the first day, the excretion by the third and fourth days may be five or six times as much. The relative amount is greater in infancy